System and method of producing metals and alloys

ABSTRACT

A system for producing an elemental material or an alloy thereof from a halide of the elemental material or halide mixtures comprising a reactor for introducing the vapor halide of an elemental material or halide mixtures thereof into a liquid phase of a reducing metal of an alkali metal or alkaline earth metal or mixtures thereof present in less than or equal to the amount needed to reduce the halide vapor to the elemental material or alloy resulting in an exothermic reaction between the vapor halide and the liquid reducing metal producing particulate elemental material or alloy thereof and particulate halide salt of the reducing metal, a chamber wherein the reaction products are cooled so that substantially all the particulate elemental material or alloy remains unsintered, and a separator for separating the particulate metal or alloy reaction products from the particulate salt.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. Ser. No. 10/530,783,filed Sep. 28, 2005; which claims priority to PCT/US03/27659, filed Sep.3, 2003, in accordance with 35 U.S.C. § 119 and § 365; which claimspriority to U.S. Provisional Application Ser. No. 60/416,611, filed Oct.7, 2002, now abandoned. The specification of each of the patentapplications listed above is expressly incorporated by reference hereinin its entirety.

BACKGROUND OF THE INVENTION

This invention relates to the production and separation of elementalmaterial from the halides thereof and has particular applicability tothose metals and non-metals for which a reduction of the halide to theelement is exothermic. Particular interest exists for titanium, and thepresent invention will be described with particular reference totitanium, but is applicable to other metals and non-metals such asaluminum, arsenic, antimony, beryllium, boron, tantalum, gallium,vanadium, niobium, molybdenum, iridium, rhenium, silicon osmium,uranium, and zirconium, all of which produce significant heat uponreduction from the halide to the metal. For the purposes of thisapplication, elemental materials include those metals and non-metalslisted above, or in Table 1, and the alloys thereof.

This invention relates to the separation methods disclosed in U.S. Pat.No. 5,779,761, U.S. Pat. No. 5,958,106 and U.S. Pat. No. 6,409,797, thedisclosures of which are incorporated herein by reference. Theabove-mentioned '761, '106 and '797 patents disclose a revolutionarymethod for making titanium which is satisfactory for its intendedpurposes and, in fact, continuously produces high grade titanium andtitanium alloys by introducing halide vapor(s) of the element or alloyto be produced into the liquid phase of a reducing metalinstantaneously, to initiate an exothermic reaction and to control thetemperature of the reaction products by providing excess amounts ofreducing metal to absorb the heat of reaction. The present inventionresides the discovery that by introducing the halide vapor(s) of theelement or alloy to be produced into the liquid phase of a reducingmetal where the reducing metal is present in an amount equal to or lessthan the stoichiometric amount required to produce the elementalmaterial (or alloy) coupled with extraneous cooling, if necessary, ofthe reaction products, continuous production of the elemental material(or alloy) can still be obtained, while preventing the produced materialfrom sintering.

Previously, the Armstrong process used excess reducing metal to absorbheat produced during the exothermic reaction resulting in a startlingnew process. It is now believed that using an excess of halide vapor toabsorb some of the heat of reaction alone, or in combination withextraneous cooling, produces many of the benefits heretofore obtainedwith the process of the '761, '106 and '797 patents. It is also believedthat use of stoichiometric quantities of reducing metal and halide vaporin combination with extraneous cooling will produce many of the benefitsheretofore obtained with the process of the '761, '106 and '797 patents.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide amethod and system for producing metals or non-metals or alloys thereofby an exothermic reaction between vapor phase halides and a liquidreducing metal in which excess amounts of the vapor phase halides arepresent to absorb some of the heat of reaction and the products producedthereby.

Yet another object of the present invention is to provide an improvedmethod and system for producing elemental materials or an alloy thereofby an exothermic reaction of a vapor halide of the elemental material ormaterials or halide mixtures thereof in a liquid reducing metal in whichexcess vapor halide in combination with a sweep gas is used to cool theproducts of the exothermic reaction and the products produced thereby.

The invention consists of certain novel features and a combination ofparts hereinafter fully described, illustrated in the accompanyingdrawings, and particularly pointed out in the appended claims, it beingunderstood that various changes in the details may be made withoutdeparting from the spirit, or sacrificing any of the advantages of thepresent invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of facilitating an understanding of the invention, thereis illustrated in the accompanying drawings, a preferred embodimentthereof, from an inspection of which, when considered in connection withthe following description, the invention, its construction andoperation, and many of its advantages should be readily understood andappreciated.

FIG. 1 is a schematic representation of a system for practicing onemethod of the present invention;

FIG. 2 is a schematic representation of another system for practicinganother embodiment of the present invention; and

FIG. 3 is a schematic representation of another system of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIG. 1 of the drawings, there is disclosed a system 10for the practice of the invention. The system 10 includes a reactor 15generally vertically displaced in this example in a drop tower vessel16, the drop tower 16 having a central generally cylindrical portion 17,a dome top 18 and a frustoconical shaped bottom portion 19. A productoutlet 20 is in communication with the frustoconical portion 19. Thereactor 15 essentially consists of an apparatus illustrated in FIG. 2 ofU.S. Pat. No. 5,958,106, in which a tube through which liquid metalflows as a stream has inserted thereinto a halide(s) vapor so that thevapor halide(s) is introduced into the liquid reducing metal below thesurface, preferably through a choke flow nozzle and is entirelysurrounded by the liquid metal during the ensuing exothermic reaction;however, it may be that because the amount of halide is either thestoichiometric amount necessary to react with all the reducing metal, orin excess of that amount, some surface reactions may occur. In suchcase, additional process steps may be required.

A reducing metal inlet pipe 25 enters the reactor 15 near the top 18 anda vapor halide inlet 30 also enters the drop tower 16 near then top 18.However, it will be understood by a person of ordinary skill in the artthat a variety of configurations of inlet conduits may be used withoutdeparting from the spirit and scope of the present invention.

As illustrated, there is an overhead exit line 35 through which thevapor leaving reactor 15 can be drawn. The overhead exit line 35 leadsto a condenser 37 where certain vapors are condensed and dischargedthrough an outlet 38 and other vapor or gas, such as an inert gas, ispumped by a pump 40 through a heat exchanger (not shown) and line 41into the drop tower 16, as will be explained.

For purposes of illustration, in FIG. 1, there is shown a reducing metalof sodium. It should be understood that sodium is only an example ofreducing metals which may be used in the present invention. The presentinvention may be practiced with an alkali metal or mixtures of alkalimetals or an alkaline earth metal or mixtures of alkaline earth metalsor mixtures of alkali and alkaline earth metals. The preferred alkalimetal is sodium because of its availability and cost. The preferredalkaline earth metal is magnesium for the same reason.

The preferred halide(s) to be used in the process of the presentinvention is a chloride, again, because of availability and cost. Themetals and non-metals which may be produced using the subject inventionare set forth in Table 1 hereafter; the alloys of the metals andnon-metals of Table 1 are made by introducing mixed halide vapor intothe reducing metal.

TABLE FEEDSTOCK HEAT kJ/g TiCl₄ −5 AlCl₃ −5 SbCl₃ −4 BeCl₂ −6 BCl₃ −8TaCl₆ −4 VCl₄ −6 NbCl₅ −5 MoF₅ −10 GaCl₃ −5 UF₆ −4 ReF₆ −8 ZrCl₄ −4SiCl₄ −11

All of the feedstocks (in various combinations) as chlorides or otherhalides in Table 1 result in an exothermic reaction with an alkali metalor alkaline earth metal to provide the halide(s) of the reducing metaland the metal or alloy of the halides introduced into the reducingmetal. Ti is discussed only by way of example and is not meant to limitthe invention. Because of the large heat of reaction, there has been theproblem that the reaction products fuse into a mass of material which isdifficult to process, separate and purify. Discussions of the Kroll andHunter processes appear in the patents referenced above.

The patents disclosing the Armstrong process show methods and systems ofproducing a variety of metals and alloys and non-metals in which theheat of reaction resulting from the exothermic reaction is controlled bythe use of excess liquid reducing metal. The reaction proceedsinstantaneously by introducing the metal halide into a continuous phaseof liquid reducing metal, otherwise described as a liquid continuum, atthe temperatures illustrated. The use of a subsurface reaction describedin the Armstrong process has been an important differentiation betweenthe batch processes and other suggested processes for making metals suchas titanium and the processes disclosed in the Armstrong et al. patents.

Nevertheless, the use of excess liquid reducing metal requires that theexcess liquid metal be separated before the products can be separated.This is because the excess liquid reducing metal may explosively reactwith water or is insoluble in water, whereas the particulate products ofthe produced metal and the produced salt can be separated with waterwash.

By way of example, when titanium tetrachloride in vapor form is injectedinto sodium liquid, an instantaneous reaction occurs in which titaniumparticles and sodium chloride particles are produced along with the heatof reaction. Excess sodium absorbs sufficient heat that the titaniumparticles do not sinter to form a solid mass of material. Rather, afterthe excess sodium is removed, such as by vacuum distillation suggestedin the aforementioned Armstrong patents, the remaining particulatemixture of titanium and sodium chloride can be easily separated withwater.

Nevertheless, vacuum distillation is expensive and it is preferred tofind systems and methods that will permit the separation of theparticulate reaction products of the reaction directly with waterwithout the need of preliminary steps. This has been accomplished in thepresent invention by the discovery that using stoichiometric amounts ofreactants or excess halide vapor to absorb some of the heat of reaction,with our without extraneous cooling, significant advantages of theArmstrong process may be retained. For instance, using an excess halidevapor as a heat sink results in particulate products and only vaporphase halide which can be efficiently and inexpensively removed so thatthe particulates accumulating at the bottom 19 of the reaction vessel ordrop tower 16 are entirely free of liquid reducing metal, therebypermitting the separation of the particulate reaction products withwater, obviating the need for a separate vacuum distillation step.

In the reactor 15, as previously taught in the Armstrong patents, thecontinuous liquid phase of sodium (or other reducing metal) isestablished into which the titanium tetrachloride vapor is introducedand instantaneously causes an exothermic reaction to occur producinglarge quantities of heat, and particulates of titanium metal and sodiumchloride. The boiling point of sodium chloride is 1465° C. and becomesthe upper limit of the temperature of the reaction products, whereas theboiling point of titanium tetrachloride is the lower limit of thetemperature of the reaction products to ensure that all excess titaniumtetrachloride remains in the vapor phase until separation from theparticulate reaction products. A choke flow nozzle also known as acritical flow nozzle is well known and is used in the line transmittinghalide vapor into the liquid reducing metal, all as previously disclosedin the '761 and '106 patents. It is critical for the present inventionthat stoichiometric quantities of reactants with extraneous cooling orthat excess halide vapor such as TiCl₄ be available with or withoutextraneous coolants to absorb the heat of reaction to control thetemperature of the reaction products.

The vapors exiting the reactor 15 are drawn through exit line 35 alongwith an inert sweep gas introduced through the inert gas inlet 41. Theinert gas, in this example, argon, may be introduced at a temperature ofabout 200° C., substantially lower than the temperature of the reactionproducts which exit the tower 16. The argon sweep gas flows, in theexample illustrated in FIG. 1, countercurrently to the direction of flowof the particulate reaction products. The excess titanium tetrachloridevapor is swept by the argon into the outlet 35 along with whateverproduct fines are entrained in the gas stream comprised of argon andtitanium tetrachloride vapor at an elevated temperature and transmittedto the condenser 37. In the condenser 37, heat exchange occurs in whichthe titanium tetrachloride vapor is cooled to about 200° C. and recycledto the titanium tetrachloride feed or inlet 30 via line 38 and the argonis also cooled to about 200° C. temperature at which it is recycled. Itis seen therefore, that the inert gas preferably flows in a closed loopand continuously recirculates as long as the process is operational. Theproduct fines present in the condenser 37 will be removed by filters(not shown) in both the titanium tetrachloride recycling line 38 and inthe line 39 exiting the condenser 37 with the inert gas.

As the inert gas moves upwardly through the vessel or drop tower 16,there is contact between the colder inert gas and the reactionparticulates which are at a higher temperature. Excess titaniumtetrachloride vapor exits the drop tower 16 at an elevated temperaturewhile the particulate product exits the reactor 15 at a temperature notgreater than 1465° C. After being cooled by contact with the argon gas,the particulate product, in this example, leaves the vessel 16 andenters a cooler (not shown), to exit therefrom at about 50° C.Thereafter, the product may be introduced to a water wash to separatethe metal particulates. The titanium particulates exit from the waterwash for drying and further processing.

It should be understood that although titanium is shown to be theproduct in FIG. 1, any of the elements or alloys thereof listed in Table1 may be produced by the method of the present invention. The mostcommercially important metals at the present time are titanium andzirconium and their alloys. The most preferred titanium alloy fordefense use is 6% aluminum, 4% vanadium, the balance substantiallytitanium. This alloy known as 6:4 titanium is used in the aircraftindustry, aerospace and defense. Zirconium and its alloys are importantmetals in nuclear reactor technology. Other uses are in chemicalprocessing equipment.

The preferred reducing metals, because of cost and availability, aresodium of the alkali metals and magnesium of the alkaline earth metals.The boiling point of magnesium chloride is 1418° C. Therefore, ifmagnesium were to be used rather than sodium as the reducing metal, thenpreferably the product temperature would be maintained below the boilingpoint of magnesium chloride. The chlorides are preferred because of costand availability.

One of the significant features of the present invention is the completeseparation of the particulate reaction products from any left overreactants as the reaction products leave the reactor 15 therebyproviding at the bottom of the drop tower 16 a product which may then beseparated with water in an inexpensive and uncomplicated process. Ifliquid sodium or other reducing metal is trapped within the productparticulates, it must be removed prior to washing. Accordingly, theinvention as described is an advance with respect to the separation ofthe metal or alloy particulates after production as disclosed in theaforementioned Armstrong et al. patents and application.

Referring to FIG. 2, there is disclosed another embodiment of thepresent invention system 110 which includes a reactor 115 disposedwithin a drop tower 116 having a cylindrical center portion 117, a dometopped portion 118 and a frustoconical bottom portion 119 connected to aproduct outlet 120. A plurality of cooling coils 121 are positionedaround the frustoconical portion 119 of the drop tower 116 for a purposeto be explained.

As in the system 10 shown in FIG. 1, there is a metal halide inlet 130and a reducing metal inlet 125 in communication with the reactor 115disposed within the drop tower 116. An overhead exit line 135 leads fromthe domed top portion 118 of the drop tower 116 to a condenser 137 influid communication with a pump 140. An excess vapor and product fineoutlet 138 is also provided from the condenser 137. In operation, thesystem 110 is similar to the system 10 in that a liquid reducing metal,for instance sodium or magnesium, is introduced via inlet 125 from asupply thereof at a temperature above the melting point of the metal,(the melting point of sodium is 97.8° C. and for Mg is 650° C.) such as200° C. for sodium and 700° C. for Mg. The vapor halide of the metal oralloy to be produced, in this example, titanium tetrachloride, isintroduced from the boiler at a temperature of about 200° C. to beinjected as previously discussed into a liquid so that the entirereaction occurs instantaneously and is at least initially subsurface.The products coming from the reactor 115 include particulate metal oralloy, and particulate salt of the reducing metal. Also, excess vaporhalide of the metal or alloy to be produced may be present. In thesystem 110, there is no sweep gas, but the drop tower 116 is operated ata pressure slightly in excess of 1 atmosphere and this, in combinationwith the vacuum pump 140, causes any excess vapor halide leaving thereactor 115 to be removed from the drop tower 116 via the line 135. Acertain amount of product fines may also be swept away with the halidevapor during transportation from the drop tower 116 through thecondenser 137 and the excess titanium tetrachloride vapor outlet 138. Afilter (not shown) can be used to separate any fines from the vapor inline 138.

Cooling coils 121 are provided, as illustrated on the bottom portion 119of the drop tower 116. A variety of methods may be used to cool the droptower 116 to reduce the temperature of the product leaving the droptower 116 through the product outlet 120. As illustrated in FIG. 2, aplurality of cooling coils 121 may be used or alternatively, a varietyof other means such as heat exchange fluids in contact with thecontainer or heat exchange medium within the drop tower 116. What isimportant is that the product be cooled while the excess TiCl₄ remains avapor so that the vapor phase can be entirely separated from the productprior to the time that the product exits the drop tower 116 through theproduct outlet 120.

Referring now to FIG. 3, there is disclosed another embodiment of theinvention. A system 210 in which like parts are numbered in the 200series as opposed to the 100 series. Operation of the system 210 issimilar to the operation of the system 10, but in the system 210, aninert sweep gas flows co-currently with the product, as opposed to thecountercurrent flow as illustrated in system 10 and FIG. 1. In thesystem 210 illustrated in FIG. 3, the gas flow is reversed in comparisonto the system 10. In the system 210, the sweep gas such as argon, theexcess (if any) titanium tetrachloride vapor, and the product oftitanium particles and sodium chloride exit through the outlet 220 intoa demister or filter 250. The demister or filter 250 is in fluidcommunication with a condenser 237 and a pump 240 so that the excesstitanium tetrachloride (if any) vapor and the argon along with whateverfines come through the demister or filter 250 are transported via aconduit 252 to the condenser 237. In the condenser 237, the excesstitanium tetrachloride vapor is cooled, the fines are separated whilethe argon or inert gas is cooled and recycled via the pump 240 in line235 to the drop tower 216. The inert gas may have to be separated fromexcess titanium tetrachloride, which can be accomplished by appropriatecondensing of the TiCl₄. The other apparatus of the system 210 bearnumbers in the 200 series that correspond to the numbers in the system10 and 100 and represent the same part functioning in the same orsimilar manner.

It is seen that the present invention can be practiced with a sweep gasthat is either countercurrent or co-current with the reaction productsof the exothermic reaction between the halide and the reducing metal orwithout a sweep gas. An important aspect of the invention is theseparation of any excess halide vapor prior to the separation of theproduced metal and the produced salt. Because excess halide vapor isused as a heat sink or a cooling gas to control the temperatures of thereaction products due to the large heat of reaction, it is possible thatconditions may be present which do not occur with the processes taughtin the Armstrong et al. '761 or '106 patents. For instance, whentitanium tetrachloride is present in excess of the stoichiometric amountneeded to react with the reducing metal, certain subchlorides, such asTiCl₃ or TiCl₂, may be formed. Subchlorides are to be avoided, sincethey may contaminate the produced titanium, requiring furtherprocessing. Moreover, it is possible that some of the reaction betweenthe reducing metal, for instance, sodium, and the halide, for instance,titanium tetrachloride, may not be subsurface. This is not preferredbecause the thermodynamics of a surface reaction are different than asubsurface reaction.

Various alloys can be made using the process of the present invention.For instance, titanium alloys including aluminum and vanadium can bemade by introducing predetermined amounts of aluminum chloride andvanadium chloride and titanium chloride to a boiler or manifold and themixed halides introduced into liquid reducing metal. For instance, grade5 titanium alloy is 6% aluminum and 4% vanadium. Grade 6 titanium alloyis 5% aluminum and 2.5% tin. Grade 7 titanium is unalloyed titanium andpaladium. Grade 9 titanium is titanium alloy containing 3% aluminum and2.5% vanadium. Other titanium alloys include molybdenum and nickel andall these alloys may be made by the present invention.

Accordingly, there has been disclosed an improved process for making andseparating the products of the Armstrong process resulting from theexothermic reaction of a metal halide with a reducing metal. A widevariety of important metals and alloys can be made by the Armstrongprocess and separated according to this invention.

While there has been disclosed what is considered to be the preferredembodiment of the present invention, it is understood that variouschanges in the details may be made without departing from the spirit, orsacrificing any of the advantages of the present invention.

1. A method of producing an elemental material or an alloy thereof froma halide of the elemental material or halide mixtures comprisingintroducing the vapor halide of an elemental material or halide mixturesthereof into a liquid phase of a reducing metal of an alkali metal oralkaline earth metal or mixtures thereof present in less than or equalto the amount needed to reduce the halide vapor to the elementalmaterial or alloy resulting in an exothermic reaction between the vaporhalide and the liquid reducing metal producing particulate elementalmaterial or alloy thereof and particulate halide salt of the reducingmetal, cooling the reaction products so that substantially all theparticulate elemental material or alloy remains unsintered, andseparating the particulate reaction products.
 2. The method of claim 1,wherein the elemental material or alloy is one or more of Ti, Al, Sb,Be, B, Ga, Mo, Nb, Ta, V, Zr, U, Re, Si, Os, Ir and mixtures thereof. 3.The method of claim 2, wherein the reducing metal is an alkali metal. 4.The method of claim 3, wherein the reducing metal is Na.
 5. The methodof claim 4, wherein the elemental material or an alloy thereof includestitanium and the Na is flowing.
 6. The method of claim 2, wherein thereducing metal is an alkaline earth metal.
 7. The method of claim 6,wherein the reducing metal is Mg.
 8. The method of claim 7, wherein theelemental material or alloy thereof includes titanium and the Mg isflowing.
 9. The method of claim 2, wherein the alloy is substantially Tiand Al and V and is formed by introducing the chlorides thereof as vaporinto a liquid phase of a reducing metal.
 10. The method of claim 2,wherein the particulate reaction products are cooled with an inert sweepgas.
 11. The method of claim 9, wherein the reducing metal is Na, theinert sweep gas is Ar and the alloy is Ti-6% by weight Al-4% by weightV.
 12. The method of claim 9, wherein the reducing metal is Mg, theinert sweep gas is Ar and the alloy is Ti-6% by weight Al-4% by weightV.
 13. The method of claim 1, wherein the temperature of the particulateelemental material or alloy thereof is maintained at or below theboiling point of the halide salt of the reducing metal.
 14. The methodof claim 10, wherein the inert sweep gas flows countercurrently to theparticulate reaction products.
 15. The method of claim 10, wherein theinert sweep gas flows concurrently with the particulate reactionproducts; and further including filtering the particulate reactionproducts from the sweep gas.
 16. The method of claim 1, wherein theparticulate reaction products move in one direction and are cooled bycontact with an inert gas flowing countercurrently to the particulatereaction products, the inert gas separating any excess vapor halide ofthe elemental material or halide mixtures thereof present from theparticulate reaction products before separation of the particulatehalide salt of the reducing metal from elemental material or alloythereof.
 17. The method of claim 16, wherein the cooled particulatereaction products are contacted with water to separate the halide saltof the reducing metal from particulate elemental material or alloythereof.
 18. A method of producing a metal element or an alloy thereofin an exothermic reaction between the chloride of the metal element orthe chlorides of the constituents of the alloy and a reducing metal ofan alkali metal or an alkali earth metal or mixtures thereof, comprisingestablishing a liquid phase of the reducing metal and introducing thevapor chloride or vapor chlorides of the metal or alloy to be producedinto the liquid phase of the reducing metal in an amount equal to orless than the stoichiometric amount needed to react with the reducingmetal to produce particulate reaction products of the metal element oralloy thereof and particulate chloride salt of the reducing metal andheat, cooling the reaction products to prevent sintering of theparticulate metal element or alloy, and separating the cooledparticulate metal element or alloy from the chloride salt of thereducing metal.
 19. The method of claim 18, wherein the particulatereaction products are cooled by contact with flowing gas cooler than thereaction products.
 20. The method of claim 19, wherein the flowing gasis inert with respect to the particulate reaction products and flowsthrough the particulate products to cool the particulate reactionproducts and to separate any chloride vapor from the particulatereaction products.
 21. The method of claim 20, wherein the metal elementis Ti or alloys thereof or Zr or alloys thereof and the reducing metalis Na or an alkaline earth metal.
 22. The method of claim 21, whereinthe alkaline earth metal is Mg.
 23. The method of claim 21, wherein themetal element is Ti.
 24. The method of claim 21, wherein the alloyincludes Ti and V and Al.
 25. The method of claim 18, wherein any excesshalide vapor present is separated from the reaction products.
 26. Aproduct made by the method of claim
 1. 27. A product made by the methodof claim 18.